Telephone receiver



Nov. 1924. 1,516,680

' E; P. OSWALD TELEPHONE RECEIVER Filed July '7 1922' ndentom 62!) P Oswald.

(funny Patented Nov. 25, 1924.

UNITED STATES EARL I. OSWALD, 013 DETROIT, MICHIGAN.

TELEPHONE RECEIVER.

Application filed July '7,

To all) whom it may concern:

Be it known that I, EARL P. OSWALD, a citizen of the United States, residing at Detroit, county of Wayne, State of Michigan, have invented a certain new and useful 1111- provement in Telephone Receivers, and declare the following to be a full, clear, and exact description of the same, such as will enable others skilled in the art to which it pertains to make and use the same, reference being had to the accompanying drawings, which form a part of tlns specification.

This invention relates to telephone receivers, the object being to provide a simple construction and one in which the amplitude of vibration of the diaphragm is increased producing what is known as a loud spealr- Zing receiver. A feature of this inventlon is in the provision of an armature pivotally supported between two pairs of poles of the magnet and repelled from one pair and attracted toward the other alternately thereby, as is hereinafter described, increasing the force applied by the armature. A further feature of the invention is in the construction of the pole pieces about which the coil of the electro-magnet is wound. These and other objects and various novel fea-. tures of the invention are hereinafter more fully described and claimed, and the preferred form of device embodying my invention is shown in the accompanying drawings in which- Fig. .1. is aplan view showing my improved receiver with the cap and diaphragm removed.

Fig. 2 is a section taken on line 22 of Fig. 1.

Fig. 3 is a section on an enlarged scale taken on line 33 of Fig. 1.

Fig. 4: is an enlarged plan view of the pole structure.

Figs. 5 and 6 are details in perspective of the two pole pieces separated to show the construction and mode of assembly thereof.

The casing for the structure may be of any approved type here shown being a cup shaped member 1 preferably of non-mag netic material having an open side or end to receive a centrally apertured cap 2 and a flexible metallic diaphragm t is supported between the capand case as shown particularly in section in Fig. 2. A Q-shape'd permanent magnet 5 is positioned in the case having the ends spaced apart on; one side as 1922. Serial No. 573,265.

is shown at 6 providing the ends or poles 7 and 8, to each of which is attached respectively asheet metal pole piece 9 and 9" indicated in perspective in Figs. 5 and 6. These are preferably of soft iron and made from a blank sheet that is cut and bent to the peculiar shape there shown each piece being V-shaped in form having V-shaped legs 10 and 11 provided with parallel flanges 12 on the opposite sides and the two V members forming a pole 9 and 9 The two angular edges of the legs of each pole lie relatively at an angle one to the other. These two members are to be assembled as indicated in plan View in Fig. 4: to provide a hollow case or spool and are spaced providing a space 14 between the leg 10 of one pole on one side and the leg 10 of the other pole on the same side and the space 15 as indicated by dotted lines between the leg 11 of the member 9 and the leg 11 of the member 9: The assembled pole pieces 9 and 9" are shown in side elevation in Fig. 3, and it is to be understood that the two pole pieces when assembled form a spool having a central aperture 16 between the two members 9 and 9 which aperture in the preferred construction here shown is at a right angle to the axis of the C-shaped permanent mag net. The armature 17 may be mounted on a flexible strip 17 connected at 18 to a neutral point of the magnet 5 and extending therefrom, into the space 16 between the pole pieces 9 and 9 and the space 16 is of snfii cient width to permit the arn'iatnrc to move to some extent. The sheet metal member or pole 9 is to be attached to the end 7 of the magnet 5 which may be considered the negative pole and the member 9 is attached to the end 8 which may be considered the positive pole of the magnet 55. It is to be noted that the sheet metal member 9 is attached to the pole 7 and is therefore normally negative and also extends on both sides of the armature while the member 9 becomes positive due to its attachment to the pole 8 and also extends on both sides of the armature so that above the plane of the armature there is a north pole 10 anda south pole 10" spaced apart and below the magnet there is a north pole 11 and a south 'pole 11 spaced apart. The armature tends to move to close the gap between either of these poles.

0n the members 9 9* which; when assembled to form a hollow spool, is wound the electro-magnet coil 19, the two ends of which lead out through the case preferably in an encased cable or line .20 and in the construction here shown this line 20 should or;- tend outward through the space 6 between the poles 7 and 8. The armature support 17 may be connected directly tothe center of the diaphragm by a non'magnetic connector 21 and vibration of the armature therefore causes vibration of the diaphragm.

In the structure as above described, it is to be noted that the diaphragm t may v1- brate each side of its normal plane by magnetic influence and differs from previous receivers in this respect. In previous receivers the diaphragm usually vibrates only on one side of its normal plane. This present receiver, it is also to be noted is of the repulsion type-that is, the armature is forced away from the side nearest to which it may stand, and the space 16 of the spool in which the armature is located is greater in width than the possible movement of the diaphragm so that the armature at no time actually contacts the poles either on. the upper or under side thereof.

vVith a permanent magnet having membets 9 and 9 attached to the two poles thereof there is by influence of the permanent magnet a north pole on the upper side of the armature and a north and south pole on the under side thereof and in the construction here shown the axis of the spool formed by the core members 9 and 9 is ata right angle to the axis of the permanent magnet and depending upon the direction in which the wire is wound, one end of the spool will become a north pole and the other a south pole and also the armature 17 by influence of current in the coil will have one end a north pole and the other end a south pole. Current passing through this coil is the current variation by influence of the voice as is well understood.

As is previously described the member 9 is a U-shaped member in form having the triangular legs 10 and 11 and, as will be understood from Figs. 4, 5 and 6, the leg 10 has the major portion of the metal thereof on one side of the center plane passing at a right angle through the axis of the spool and the leg 11 has the major portion of its metal on the opposite side and likewisethe member 9 has the same structure with the legs thereof oppositely disposed. The permanent magnet tends to make both the legs 10 and 11 the north pole and both the legs 10 and 11 the south pole. In Fig. 4 the letters N and S are to be understood as indicating north pole and south pole. With the coil wound upon this type of core and current passing therethrough in one direction the tendency would be to increase the magnetic strength of the leg 10 and to decrease the magnetic strength of the leg 11 on the same end of the spool. Likewise, the magnetic strength of the leg 10 will be increased. while that of the leg ll will be dccrcasd. Thus the north pole strength of the leg 10 of the member 9 and the south pole strength of the leg 10 of the member 9 is increased while that of the legs 1.1 and 11 are decreased. Thus. on the upper side of the armature with one pulsation of the current through the coil bot-h poles l0 and 10'' will be strengthened and at the same time one end of the member 17, which is directly below the portion 10, and the other end of the member 17, which directly below the portion 10", will also be mad north and south poles and would be repelled toward the poles on the opposite side of the spool and attracted thereby because the north pole of the armature would be attracted by the south pole 11 as there is still south pole influence in the member 11 due to its attachment to the permanent magnet. Likewise the south pole end of the armature 17 will be attracted by the member 11 which still has some magnetic strength as the current passing through the coil is not suflicient to entirely counteract the influence of the permanent magnet. It is possible of course to so prepare the coil that the strength of the permanent magnet could be entirely neutralized but I prefer to provide a coil of a character to not completely neutralize the effect of the permanent magnet but to reduce the influence thereof. lllith, the fluctuations in the current of the coil induced by the voice the armature 17 is made to vibrate through repulsion and attract-ion it being repelled from one side and attracted by the other and on fluctuation of current in. the coil next repelled by the side which first attracted and attracted by the side which first re pelled. The power for vibrating the diaphragm is greater than with the usual receivers in which a diaphragm is attracted toward the pole piece of a magnet and the influence of the magnet to cause vibration of the diaphragm. In such former structures the tension of the diaphragm is depended upon to move the same in one direction. In my improved structure the diaphragm is vibrated entirely by magnetic influence and no means is employed to place a tension upon the diaphragm other than the magnetic influence of the coil and permanent magnet.

in assembling the parts it is practically impossible-to place thearmature 17 exactly in the neutral position centrally of the apere turc 16 of the coil and therefore with the current passing through the coil thev arma ture will move toward one side or the other of the said aperture and as soon as current passes through the coil, which is made to fluctuate, the armature will be caused to vibrate as stated.

Having thus fully described my invention, what l claim and desire to secure by Letters Patent of the Unites States is 1. In a telephone receiver, a permanent magnet, extensions for each pole thereof each comprising a U-shaped member, the legs of one member lying substantially in the same plane as the legs of the other and in spaced relation providing a hollow core for the coil, a coil wound on the said core, an armature in the hollow core, and a diaphragm connected at its center with the armature.

2. In a telephone receiver, a permanent magnet having pole pieces each forming halves of a hollow shell, the two halves being in spaced relation and providing an air gap on opposite sides of the shell extending diagonally in opposite directions to the axis of the shell, an armature in the hollow shell and adapted to vibrate, and a diaphragm connected with the armature and vibratable thereby substantially as described.

3. In a telephone receiver, a permanent n'iagi'iet substantially C shaped in form, a case therefor, an electro-magnet consisting of a coil and a metal core of two parts substantially U-shaped in form, the major portion of the metal of one leg being at one end of the coil and the major portion of the other leg being at the other end of the coil, the two U-shaped parts together forming a hollow core and the two similar legs of the two parts on each side of the core being in spaced relation, each U part being attached directly to a pole of the permanent magnet, an armature lying in the hollow core and tending to move toward one side or the other by influence of the permanent magnet, a flexible member supporting the armature, a diaphragm carried at the end of the casing and attached at its center to the flexible member of the armature, the extent to which the diaphragm may be flexed being less than the distance between the sides of the core.

In testimony whereof, I sign this specification.

EARL P. OSWALD. 

